Messier 66

March 1, 1780. 66.
11h 08m 47s (167d 11' 39") +14d 12' 21"
`Nebula discovered in Leo; its light is very faint & it is very close to
the preceding [M65]: They both appear in the same field
[of view] in the refractor. The comet of 1773 & 1774 has passed between
these two nebulae on November 1 to 2, 1773. M. Messier didn't see them at
that time, no doubt, because of the light of the comet.'

[Unpublished Observations of Messier's Nebulae and Clusters.
Scientific Papers, Vol. 2, p. 658]
1784, Apr. 12 (Sw. 188). A vB. mE. [very bright, much extended] nebula of
irregular figure; the extension is chiefly in the direction of the meridian
and the greatest brightness near the middle.

CCCCX. 66 M. Leonis.
AR 11h 11m 48s, Dec N 13d 52'.4
Mean Epoch of Observation: 1835.31 [April 1835]
[with a drawing of M65 and M66]
A large elongated nebula, with a bright nucleus, on the Lion's haunch,
trending np [north preceding, NW] and sf [south following, SE];
this beautiful specimen of perspective lies just 3deg south-east of Theta
Leonis. It is preceded at about 73s by another of a similar shape, which is
Messier's No. 65, and both are in the field at the
same time, under a moderate power, together with several stars. They were
pointed out by Méchain to Messier in 1780, and they appeared faint and
hazy to him [Actually, these are Messier's original discoveries]. The above
is their appearance in my instrument.
These inconceivably vast creations are followed, exactly on the same
parallel, ar Delta AR=174s, by another elliptical nebula of even a more
stupendous character as to apparent dimensions. It was discovered by
H. [John Herschel], in sweeping, and is No. 875 in his
Catalogue of 1830 [actually, probably an erroneous position for re-observed
M66].
The two preceding of these singular objects were examined by
Sir William Herschel, and his son [JH]
also; and the latter says, "The general form of elongated nebulae is
elliptic, and their condensation towards the centre is almost invariably such
as would arise from the superposition of luminous elliptic strata, increasing
in density towards the centre. In many casesthe increase of density is
obviously attended with a diminution of ellipticity, or a nearer approach to
the globular form in the central than in the exterior strata." He then
supposes the general constitution of those nebulae to be that of oblate
spheroidal masses of every degree of flatness from the sphere to the disk,
and of every variety in respect of the law of their density, and ellipticity
towards the centre. This must appear startling and paradoxical to those who
imagine that the forms of these systems are maintained by forces identical
with those which determine the form of a fluid mass in rotation; because, if
the nebulae be only clusters of discrete stars, as in the greater number of
cases there is every reason to believe them to be, no pressure can propagate
through them. Consequently, since no general rotation of such a system as one
mass can be supposed, Sir John suggests a scheme which he shows is not, under
certain conditions, inconsistent with the law of gravitation. "It must rather
be conceived," he tells us, " as a quiescent form, comprising within
its limits an indefinite magnitude of individual constituents, which, for
aught we can tell, may be moving one among the other, each animated by its
own inherent projectile force, and deflected into an orbit more or less
complicated, by the influence of that law of internal gravitation which may
result from the compounded attractions of all its parts."